The inner surface of tire casings has been coated with a tacky, non-flowing sealant material which provides or tends to provide a sealing of the tire around an object which punctures the tire. A method for lining a tire with such a sealant is disclosed in U.S. Pat. No. 4,418,093. A particularly successful type of tire lining material is a tacky self-healing elastomer. The use of such elastomers has been limited to tubeless type tires. By its very nature, a self-healing elastomeric lining, adhered to the inner tread surface and sidewall of a tire casing, will have a tacky surface similar to the sticky surface of contact paper. It is this tackiness that allows the elastomer to heal and prevent the loss of air from a lined pneumatic tire when it is penetrated by a sharp object. The elastomer bonds to the surface of the penetrating object and thereby closes off any opening through which the pressurized air in the casing can escape. When the object is withdrawn, the tacky walls of the elastomer close upon themselves and fuse. Thereby, again preventing the escape of the compressed air in the tire.
Prior to this invention, only tubeless type tires could be lined with self-healing elastomers. It is virtually impossible to install and inflate a rubber inner tube into a tire casing that is lined with a tacky adhering material. A tube installed in such a manner would not inflate uniformly, but rather it would distort the lining by dragging it out of shape as various tube-to-liner adhered sections moved under filling pressure to conform to the tire casing. Such a distortion would create an imbalance that would make the tire useless in commerce.
Accordingly, one object of the present invention is to provide an improved process for lining a tire with a tacky elastomeric material and using an inner tube in that tire. Another object of the present invention is to provide a material which will temporarily convert the surface of a tacky elastomeric tire lining material to a non-tacky material.
Yet another object of the present invention is to provide an improved tire comprising a casing, tacky elastomeric material on the inner surface of the casing and a tube disposed within the casing.
These and other objects of the invention are accomplished by using a process and material which makes it possible to provide for a tire containing an inner tube which also contains a tacky elastomeric sealant. Such a tire is obtained by first applying the elastomeric sealant to either the inner surface of the tire casing or the outer surface of the inner tube. After application of the elastomeric sealant, an anti-tack material, a plasticizer that will migrate from the surface into the body of the elastomer, may be applied to the surface of the elastomer. The elastomer can be coated with the anti-tack material or plasticizer by painting, spraying, spin application, etc. The inner tube can then be inserted and inflated without undue adherence between the inner tube and casing.
In another typical application, the inner surface of the tire casing is coated with a tacky elastomer sealant. The rubber inner tube is then coated with the anti-tack material or plasticizer material. The inner tube, thus lubricated with anti-tack material or plasticizer, can then be easily inserted into the lined tacky tire casing and inflated without any distortion of the liner. After a reasonable period of time, depending upon the rate of migration under pressure of the plasticizer, the surface of the liner will again become tacky and bond to the inner tube. This method creates a system wherein the self-healing elastomeric liner is bonded both to the tire casing and the inner tube and will resist the loss of pressurized air when the system is punctured.